Admiring a professionally made sailplane fiberglass
fuselage is a common occurrence for many of us RC sailplaners.We do it at contests and at our own flying field.For example, the Artimus, NYX, Eraser, etc. all have beautiful
workmanship.So the idea of
making a fiberglass fuselage with our own hands is naturally a daunting
one.The Houston Hawk project
addresses this anxiety head on because we will be laying up our own
personal fuselage.This
document, in addition to actually making your own personal fuselage, will
help ease the anxiety.With
instruction from professional fuselage maker Don Cleveland and just paying
attention to a few details along the way, your fuselage will be strong and
beautiful.

Safety

There are a few safety
issues in making this fuselage.

Eye
Protection:Itís best
to use eyewear to protect from cloth fibers and epoxy splatters.Bring your own glasses/safety glasses to Donís house and wear
them as you work.

Gloves:Its possible to develop sensitivity to uncured epoxy.Don provides latex gloves for us to use.If you already have sensitivity, you might consider vinyl
gloves or have someone else make the fuselage for you.

Ventilation:Don keeps the garage door open during the process.If you already have a respitory problem, maybe a fan would
help.Epoxy fumes are not strong, but they do exist.There is no polyester smell to this epoxy.

Touch:When removing the cured fuselage from the mold, be very
careful.Cured epoxy and
cloth can be like needles.Avoid
running your hand down the fuselage until the cleanup, sanding and
smoothing has been done on the seams, canopy and fin.

The Mold

The quality of the mold is
of utmost importance for a straight flying sailplane.The mold for the Condor is in two pieces, a right side and a left
side.There is also a
separate mold for the canopy. Fortunately, the mold we are using is
already made and is extremely well done.It is the Condor mold that was used in the late 90ís for the
Condor kit that was distributed by Sleggherís.

I have one of the Condor kits at
home and the fuselage is great.Itís
total unpainted weight, including canopy, is 8.4 oz.The fuselage I made on October 4th weighs 9.4 oz
including the white Krylon paint.So our fuselages are in the ballpark.

Preparing the Mold

This is the first important
detail.In order to keep the
epoxy from sticking to and ruining the mold, it has to be 1) cleaned
thoroughly with alcohol, 2) waxed with Carnauba car wax, 3) apply PVA mold release, and if desired 4) sprayed with 4-6 light coats of Krylon
paint.This process takes 2
or three days elapsed time.Fortunately
for me, Don prepared the mold.He
has a vested interest in preserving it.

Cutting the Cloth

All of the cloth should be cut to size prior to
mixing any epoxy.There are
six layers of cloth used in this fuselage resulting in a very strong
structure.The cloth has to
be cut to size for both sides of the mold.Here is the sequence of cloth application:

1.5
oz fiberglass used the entire length,

6
oz fiberglass used from nose to the middle of the wing,

6
oz fiberglass used in the wing area,

6
oz fiberglass around wing saddle area

strip
of Kevlar used from the wing TE to just past the fin LE

6
oz fiberglass used the entire length

There are two layers of
fiberglass used on the canopy, 1.5 oz and 6 oz. Again, having a
professional show you where to put the cloth is a detail that results in a
strong, good-looking fuselage.

Mixing the Epoxy

Don has a preferred brand
of epoxy (MGS).It is clear and
has a pot life of one hour.You
will be mixing about three batches during the lay-up process.For consistent pot life, epoxy is best mixed by weight rather than
by volume.Don has a scale
for us to use.

Applying the Cloth with Epoxy

Using a foam brush, paint on a semi-thick layer of
epoxy to the first half of the mold.

Before applying any cloth, mix a
small slurry of epoxy and cab-o-sil into toothpaste consistency.Apply the slurry to the mold with a stick in areas with sharp
corners and radiuses such as the wing root area and around the canopy
indentation line.

When complete, lay the first layer of 1.5 oz cloth in the
mold.Starting at one end, use the foam brush to push the cloth into the
epoxy already on the mold.Get
more on the brush when needed.Don
will advise you on the amount of epoxy to use.Just remember, epoxy is thicker than water and it takes more time
for it to soak into the cloth.Be
patient on the wet-out.Two
small details to remember are 1) dob your brush on the cloth to force
epoxy in, and 2) always brush in the same direction when smoothing puddles
and cloth.

Apply the
subsequent layers of cloth in the same manner.If air bubbles or voids appear and you cannot get them out with the
brush, use your finger.

When the first half of the
mold is finished, then repeat the same process
with the other half.

Final Steps

When the epoxy on the first half of the
mold starts
getting green (stiff) the two halves of the mold will be joined together
to make a single fuselage.Sounds
simple, but there are a few preparatory steps:

On
one side of the mold, dob epoxy onto the cloth on the topside of the
fuselage to about Ĺ inch extending from the mold.

On
the other mold half, dob epoxy onto the cloth on the bottom-side of
the fuselage to about Ĺ inch extending from the mold.

With
a pair of curved-tip scissors supplied by Don, trim the cloth as
follows: On the side of the mold where the epoxy was applied to the
cloth on the top-side, trim the cloth on the top-side to a length of
3/8 inch extending from the mold.Trim the cloth on the bottom-side even with the mold.Don will show you where to taper the cloth at the nose.Trim the cloth on the fin LE even with the mold on both sides.

On
the other half of the mold where the epoxy was applied to the cloth
on the bottom-side, trim the cloth on the bottom-side to a length of
3/8 inch extending from the mold.Trim the cloth on the topside even with the mold.

With a stick, place a bead of epoxy next to the cloth around the
entire perimeter of both halves of the mold and make sure the cloth
extending from the mold is perpendicular to the mold.

Place one half of the mold on the workbench.Then take the other mold half and, using a short sideslip
motion, slide the two halves together.Quickly look at the inside through the fin and through the
canopy area to see if there are any bad folds at the seams.If there are, straighten them up.When satisfied, put the bolts through the holes and tighten the
two halves together.

Immediately,
use the rollers-on-a-stick that Don provides to reach into the
fuselage via the fin and canopy area and roll the extending cloth flat
onto the cloth on the other half of the mold.The 3/8-inch of cloth you left on the top and bottom sides are
now layered onto the opposite half.This is the magic step that bonds both halves together.

Mix
another slurry of epoxy and micro-balloons into a toothpaste
consistency.Liberally
apply the slurry to the fin LE inside the mold.Smooth it out with your finger or stick.

Turn
the fuselage nose down and drop a blob of slurry inside the nose.

When
satisfied, stand the assembled mold on its nose and let it setup
about 24 hours.

Hatching and Cleaning

After 24 hours, remove the bolts from the
mold and
pull the halves apart.To me
it sounds like a ripe watermelon splitting open.The beautiful, bright, gleaming fuselage jumps right out.Even though there is epoxy flashing to be cleaned off the
seam lines, the quality is readily apparent.All that needs to be done is to carefully cut and scrape the
flashing away from the seams and to smooth out the canopy area and fin
area with razor blades, sandpaper and dremel tool.Be very careful doing this, the cured epoxy and cloth can be like
needles.Avoid running your
hand down the fuselage until the cleanup and smoothing has been done.Wash off the PVA mold release with soap and water after you sand
off all the flashing.Do not
use a solvent to remove the mold release.

Summary

The description outlined above highlights the things
I learned in the process of making my own fiberglass sailplane fuselage
with Don.They represent the
mechanical steps and a few insights.There are many other things I observed that will only make sense to
me and are now stored into my cumulative knowledge database of my favorite
RC activity.Before I started
on this project, I had the book knowledge.Now I have the experience.Many
thanks to Don Cleveland for offering his time, tools and experience for
this club project.